Since being discovered in 1991, CNTs have been synthesized by numerous methods such as laser vaporization, arc discharge, pyrolysis, plasma-enhanced chemical vapor deposition, and thermal chemical vapor deposition. CNT yarns can be made of CNTs as disclosed in U.S. Pat. No. 7,045,108 incorporated by reference thereto. The CNT yarns would enable macroscopic CNT devices and structures to be constructed.
CNT yarns can be also be utilized as field emission source because ends of CNT yarns have a good field emission property. However, different CNT yarns may have different field emission properties depending on differing CNT yarn end shapes. Different CNT yarns usually have quite different CNT yarn end shapes. Moreover, CNT yarn length is difficult to control. Therefore, production of multiple CNT yarns with similar field emission properties has proved problematic.
It is therefore desirable to find a new manufacturing method which can overcome the above mentioned problems.